嵌埋在SiO2基质中的nc-Ge的制备及其发光现象

采用等离子体化学汽相淀积技术生长a-Ge_xSi_1-x∶H薄膜，然后在800℃，10⁵Pa下于传统开口管式炉中氧化热处理，制备嵌埋在SiO₂中的nc-Ge微晶粒．利用傅里叶变换红外光谱、喇曼光谱和X射线衍射谱分析样品的微结构，研究a-Ge_xSi_1-x∶H薄膜的氧化过程中发生的化学和物理变化，并用平衡态化学反应热理论加以解释．在某些样品中观察到室温下的光致发光现象，采用Brus电 关键词：

PREPARATION OF nc-Ge EMBEDDED IN SiO2 MATRIX AND OBSERVATION OF VISIBLE PHOTOLUMINESCENCE

The nanocrystalline(nc) Ge embedded in SiO₂ matrix was attempted to synthesize from thermal oxidation of PECVD deposited ａ-Ge_xSi_1-x∶H films.The microstructures of the samples were detected by Fourier transform infrared spectroscopy,Raman spectroscopy and XRD.The results reveal that Ge nanocrystals form during oxidation and their numbers and sizes are varied with different Ge content in the as deposited ａ-Ge_xSi_1-x∶H alloy and also changed upon different-oxidation conditions.These characteristics may be due to the selective oxidation of Si in ａ-Ge_xSi_1-x∶H alloy and the reduction of hydrogen existing in the samples in view of chemical thermodynamic equilibrium. Some nc-Si samples display visible photoluminescence(PL) at room temperature.Based on Brus, exiton three-dimensional quantum confinement model,the nc-Ge size was evaluated from the PL peak positions and show a good agreement with the result of XRD.All the above analyses suggest that nc-Ge buried in SiO₂ matrix can be obtained by the present method and its visible photoluminescence is related to the effect of quantum size on nc-Ge.The observation of nc-Ge with TEM is required to further confirm these facts.